Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2022 September 11

Planets of the Solar System: Tilts and Spins
Video Credit: NASA, Animation: James O'Donoghue (JAXA)

Explanation: How does your favourite planet spin? Does it spin rapidly around a nearly vertical axis, or horizontally, or backwards? The featured video animates NASA images of all eight planets in our Solar System to show them spinning side-by-side for an easy comparison. In the time-lapse video, a day on Earth -- one Earth rotation -- takes just a few seconds. Jupiter rotates the fastest, while Venus spins not only the slowest (can you see it?), but backwards. The inner rocky planets across the top underwent dramatic spin-altering collisions during the early days of the Solar System. Why planets spin and tilt as they do remains a topic of research with much insight gained from modern computer modeling and the recent discovery and analysis of hundreds of exoplanets: planets orbiting other stars.

Tomorrow's picture: stars and sprites


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